The overall objective is to study clinical and mechanical regulators of alveolar surface active material (SAM) (pulmonary surfactant). The initial three goals, study of the effects of isoxsuprine, premature rupture of the membranes, and constant distending airway pressure, have been addressed and resulted in publications (section IV). This year, we will explore further the relationship of material diabetes and fetal lung development. Measures of surface tension and saturated lecithin in fetal lung fluid, and SAM precursor incorporation rates in fetal lung slices and tissue culture will be carried out. We will continue our studies of catecholamine infusions into fetal sheep and its effects on SAM in tracheal effluent. Acute studies were completed this past year, and we plan a set of chronic experiments this winter. BIBLIOGRAPHIC REFERENCE: Robert, M.F., Neff, R.K., Hubbell, J.P., Taeusch, H.W., and Avery, M.E.: Association between maternal diabetes and the respiratory distress syndrome in the newborn. New Eng. J. Med. 294:357-360, 1976. Lawson, E., and Taeusch, H.W.: Prenatal glucocorticoids for prevention of the respiratory distress syndrome. Medical Letter 18, #14, July 2, 1976.